CREEP RUPTURE OF WATER-ABSORBED GREEN COMPOSITE

The creep rupture properties of a water-absorbed green composite were examined and assessed for long-term safety. Plain woven jute fiber cloth was used as a reinforcement and a poly-lactic acid (PLA) resin sheet was used as a matrix. A water-absorption test of this green composite was conducted at room temperature, for 24 hours: The water absorption rate at 24 hours was 8%. Quasistatic tensile tests of water-absorbed green composites were conducted at a crosshead speed 0.1, 1.0 and 10 mm/min; as well as on non-water-treated control material. Tensile creep tests of the nonwater-treated and 8% water-absorbed green composites were conducted. The environmental temperature was room temperature. The maximum test time was 100 hours. We found that Young’s modulus and tensile strength of the non-water-treated and the 8% water-absorbed green composite increased with an increase in the strain rates. Young’s modulus and tensile strength of the 8% waterabsorbed green composite were lower than those of the non-water-absorbed green composite, under all strain rates. Creep rupture strengths of the non-water-absorbed and the 8% water-absorbed green composites decreased with an increase of loading time. The creep rupture life of the 8% waterabsorbed green composite was lower than that of the non-water absorbed green composite. Generally, the glass transition temperature of PLA resin was decreased by water absorption; therefore, the creep rupture property of the green composite studied was mainly affected, due to a decrease of the viscoelasticity of the matrix by water absorption.